DE69427912T2 - MACHINE DISHWASHER CONTAINING AN OXYGEN BLENDER, PARAFFIN OIL AND BENZOTRIAZOLE COMPOUNDS AS AN INHIBITOR OF SILVER tarnishing - Google Patents

Abstract

There is provided a bleaching composition, suitable for use in a machine dishwashing method, containing: an oxygen-releasing bleaching agent, from 0.05 % to 2.5 % by weight, preferably 0.1 % to 0.6 % by weight of a paraffin oil, from 0.005 % to 3 %, preferably from 0.02 % to 1 % and most preferably from 0.05 % to 0.5 % by weight of a benzotriazole compound. Preferably the bleaching composition forms part of a detergent composition.

Description

The present invention relates to automatic dishwashing detergent compositions which exhibit bleachable stain removing and improved silver tarnishing properties.

Compositions intended for use in automatic dishwashing machines are well known and there have been ongoing efforts by detergent manufacturers to improve the cleaning and/or rinsing efficiency of the compositions on tableware and glassware, as reflected in numerous patent publications.

The present invention addresses the problem of silver tarnishing encountered when bleaching compositions containing oxygen bleaching species are used in machine dishwashing processes.

The satisfactory removal of bleachable stains such as tea, fruit juice and colored vegetable soil stains such as carotenoid stains is a special challenge for the formulator of an automatic dishwashing detergent composition. Traditionally, the removal of such stains has been made possible by the use of bleaching components, such as oxygen and chlorine bleaches.

One problem encountered when using such bleaches is tarnishing of silver components in the wash load. Oxygen bleaches are more likely to cause the tarnishing problem than chlorine bleaches. The degree of tarnishing observed can range from a slight discoloration of the silverware to the formation of a dense black coating on the surface of the silverware.

The formulator is thus faced with the dual challenge of formulating a product that maximizes the cleaning of bleachable stains, but minimizes the occurrence of tarnishing of silverware components of the wash load.

Applicants have found that the tarnishing problem can be particularly severe when an oxygen bleach species is used, especially when the formulation has a pH below 9.6. However, oxygen bleach species are preferred over chlorine bleaches for environmental reasons.

It was found that improved silver anti-tarnishing and good cleaning performance could be achieved by the combined use of a paraffin oil, a benzotriazole compound and the regulation of oxygen bleaching power.

Preferably, the Release of oxygen bleach is also controlled. The rate of release of oxygen bleach is preferably fast enough to provide satisfactory cleaning, but not so fast as to allow tarnishing. In particular, the rate of release of any organic peroxyacid species into the wash solution is preferably controlled.

It is an object of the present invention to provide compositions suitable for use in machine dishwashing processes which have improved silver anti-tarnishing properties and good cleaning performance, particularly bleachable stain removal performance.

The present compositions are based on oxygen bleaching species and are preferably in compact form and have a pH of 9.6 or higher.

The use of benzotriazoles as corrosion inhibitors is described in FR-A-1 209 904, US-A-4 620 936 and EP-A-135 226. The use of paraffin oils in machine dishwashing is described in US-A-5 089 162, US-A-4 919 834 and DE-A-41 21 307.

EP-A-0 150 387 describes machine dishwashing detergent compositions based on chlorine bleaches which contain a paraffin wax as a foam suppressor. EP-A-0 180 088 describes machine dishwashing detergent compositions based on carbonates and silicates which contain paraffin oils as dust binding agents.

According to the invention there is provided an automatic dishwashing detergent composition having bleachable stain removing and silver tarnishing preventing properties, comprising:

- an oxygen-releasing bleaching agent, the proportion of oxygen-releasing agent being such that the proportion of available oxygen, measured according to the method described herein, is 0.3 to 2.5% by weight, preferably 0.5 to 1.7% by weight;

- 0.05 to 2.5% by weight, preferably 0.1 to 0.6% by weight of a paraffin oil; and

- 0.005 to 3 wt.%, preferably 0.02 to 1 wt.%, and most preferably

- 0.05 to 0.5 wt.% of a benzotriazole compound,

Preferably, the rate of release of available oxygen is such that available oxygen is completely released from the composition in a time interval of from 3.5 minutes to 10.0 minutes using the test protocol described in the present specification.

The present compositions contain as essential components an oxygen releasing bleaching species, a benzotriazole compound and a paraffin oil. The level of available oxygen is controlled. Preferably, the rate of release of available oxygen and organic peroxyacid bleaching species is also controlled.

Oxygen-releasing bleach

The first essential feature of the compositions of the invention is a bleaching agent selected from oxygen releasing agents such as inorganic perhydrate salts, peroxyacid bleach precursors, organic peroxyacids and mixtures thereof.

Inorganic perhydrate bleaches

Examples of inorganic perhydrate salts include perborate, percarbonate, perphosphate, persulfate and persilicate salts. The inorganic perhydrate salts are normally the alkali metal salts. The inorganic perhydrate salts can be enclosed as a crystalline solid without additional protection. For certain perhydrate salts, however, the preferred embodiments of such granular compositions use a coated form of the material which provides improved storage stability for the perhydrate salt in the granular product.

Sodium perborate can exist in the form of the monohydrate of nominal formula NaBO₂H₂O₂ or the tetrahydrate NaBO₂H₂O₂.3H₂O.

Sodium percarbonate, which is a preferred perhydrate for inclusion in compositions according to the invention, is an addition compound of the formula corresponding to 2Na₂CO₃.3H₂O₂ and is commercially available as a crystalline solid. The percarbonate is most preferably incorporated into such compositions in a coated form which provides product stability.

A suitable coating material which provides product stability comprises a mixed salt of a water soluble alkali metal sulphate and carbonate. This coating, however, allows rapid release of the percarbonate bleach into the wash solution and is therefore not a suitable means for providing controlled release of the percarbonate bleach into a wash solution. Such coatings together with coating processes are previously described in GB-1 466 799 which was awarded to Interox on 9 March 1977. The weight ratio of the mixed salt coating material to the percarbonate is in the range of 1:200 to 1:4, more preferably 1:99 to 1:9, and most preferably 1:49 to 1:19. Preferably, the mixed salt consists of sodium sulfate and sodium carbonate, which has the general formula Na₂SO₄.n.Na₂CO₃ when n is 0.1 to 3, preferably 0.3 to 1.0, and most preferably 0.2 to 0.5.

Other coatings containing silicate (alone or with borate salts or boric acids or other inorganic substances), waxes, oils, fatty soaps, can also be used advantageously within the present invention.

Potassium peroxymonopersulfate is another inorganic perhydrate salt used in the compositions described herein. Another perhydrate is monoperoxyphthalic acid.

Inorganic perhydrate salts are normally incorporated in the form of the sodium salt in an amount of from 1 to 40%, more preferably from 2 to 30%, and most preferably from 5 to 25% by weight of the compositions.

Peroxyacid bleach precursors

Suitable peroxyacid bleach precursors typically contain one or more N- or O-acyl groups, which precursors can be chosen from a wide range of classes. Suitable classes include imides and acylated derivatives of imidazoles and oximes, and examples of useful materials within these classes are described in GB-A-1 586 789.

Suitable esters are described in GB-A-836 988, 864 798, 1 147 871, 2 143 231 and EP-A-0 170 386. The acylation products of sorbitol, glucose and all saccharides with benzoylating agents and acetylating agents are also useful.

Specific O-acylated precursor compounds include 2,3,3-trimethylhexanoyloxybenzenesulfonates, benzoyloxybenzenesulfonates, nonanoyl-6-aminocaproyloxybenzenesulfonates, monobenzoyltetraacetylglucose, benzoyl peroxide and cationic derivatives of any of the above, including the alkylammonium derivatives and pentaacetylglucose. Phthalic anhydride is a suitable anhydride-type precursor.

Specific cationic derivatives of the O-acyl precursor compounds include 2- (N,N,N-trimethylammonium)ethylsodium 4-sulfophenyl carbonate chloride and any of the alkylammonium derivatives of the benzoyloxybenzenesulfonates, including the 4-(trimethylammonium)methyl derivative.

Useful N-acyl compounds are described in GB-A-855 735, 907 356 and GB-A-1 246 338.

Preferred imide-type precursor compounds include N-benzoylsuccinimide, tetrabenzoylethylenediamine, N-benzoyl-substituted ureas and the N,N,N¹,N¹-tetraacetylated alkylenediamines in which the alkylene group contains 1 to 6 carbon atoms, especially those compounds in which the alkylene group contains 1, 2 and 6 carbon atoms. Tetraacetylethylenediamine (TAED) is particularly preferred.

N-acylated precursor compounds of the lactam class are generally described in GB-A-955 735. While the broadest aspect of the invention contemplates the use of any lactam suitable as a peroxyacid precursor, preferred materials include the caprolactams and valerolactams.

Suitable N-acylated lactam precursors have the formula:

wherein n is 0 to 8, preferably 0 to 2, and R6 is H, an alkyl, aryl, alkoxyaryl or alkaryl group having 1 to 12 carbons, or a substituted phenyl group having 6 to 18 carbon atoms.

Suitable caprolactam bleach precursors have the formula:

wherein R¹ is H or an alkyl, aryl, alkoxyaryl or alkaryl group having 1 to 12 carbon atoms, preferably 6 to 12 carbon atoms, most preferably R¹ is phenyl .

Suitable valerolactams have the formula:

wherein R¹ is H or an alkyl, aryl, alkoxyaryl or alkaryl group having 1 to 12 carbon atoms, preferably 6 to 12 carbon atoms. In highly preferred embodiments, R¹ is selected from phenyl, heptyl, octyl, nonyl, 2,4,4-trimethylpentyl, decenyl and mixtures thereof.

The most preferred materials are those which are normally solid at <30°C, especially the phenyl derivatives, i.e. benzoylvalerolactam, benzoylcaprolactam and their substituted benzoyl analogues such as chloro, aminoalkyl, alkyl, aryl and alkoxy derivatives.

Caprolactam and valerolactam precursors in which the R¹ moiety contains at least 6, preferably 6 to 12 carbon atoms, provide peroxyacids upon perhydrolysis of a hydrophobic character which provide nucleophilic cleaning. Precursor compounds in which R¹ comprises 1 to 6 carbon atoms provide hydrophilic bleaching species which are particularly efficient for bleaching beverage stains. Mixtures of 'hydrophobic' and 'hydrophilic' caprolactams and valerolactams, typically in weight ratios of 1:5 to 5:1, preferably 1:1, can be used herein for stain removal benefits for mixed stains.

Highly preferred caprolactam and valerolactam precursors include: benzoyl caprolactam, nonanoyl caprolactam, benzoyl valerolactam, nonanoyl valerolactam, 3,5,5-trimethylhexanoyl caprolactam, 3,5,5-trimethylhexanoyl valerolactam, octanoyl caprolactam, ocatanoyl valerolactam, decanoyl caprolactam, decanoyl valerolactam, Undecenoylcaprolactam, undecenoylvalerolactam, (6-octanamidocaproyl)oxybenzenesulfonate, (6-nonanamidocaproyl)oxybenzenesulfonate, (6-decanamidocaproyl)oxybenzenesulfonate, and mixtures thereof. Examples of highly preferred substituted benzoyl lactams include methyl benzoyl caprolactam, methyl benzoyl valerolactam, ethyl benzoyl caprolactam, ethyl benzoyl valerolactam, propyl benzoyl caprolactam, propyl benzoyl valerolactam, isopropyl benzoyl caprolactam, isopropyl benzoyl valerolactam, butyl benzoyl caprolactam, butyl benzoyl valerolactam zoylcaprolactam, tert-butylbenzoylvalerolactam, pentylbenzoylcaprolactam, pentylbenzoylvalerolactam, hexylbenzoylcaprolactam, hexylbenzoylvalerolactam, ethoxybenzoylcaprolactam, ethoxybenzoylvalerolactam, propoxybenzoylcaprolactam, propoxybenzoylvalerolactam, isopropoxybenzoylcaprolactam , isopropoxybenzoylvalerolactam, butoxybenzoylcaprolactam, butoxybenzoylvalerolactam, Tertbutoxybenzoylcaprolactam, Tertbutoxybenzoylvalerolactam, Pentoxybenzoylcaprolactam, Pentoxybenzoylvalerolactam, Hexoxybenzoylcaprolactam, Hexoxybenzoylvalerolactam, 2,4,6-Trichlorobenzoylcaprolactam, 2,4,6-Trichlorobenzoylvalerolactam, Pentafluorobenzoylcaprolactam, Pentafluorobenzoylvalero lactam, dichlorobenzoylcaprolactam, dimethoxybenzoylcaprolactam, 4-chlorobenzoylcaprolactam, 2,4-dichlorobenzoylcaprolactam, terephthaloyldicaprolactam, pentafluorobenzoylcaprolactam, Pentafluorobenzoylvalerolactam, dichlorobenzoylvalerolactam, dimethoxybenzoylvalerolactam, 4-chlorobenzoylvalerolactam, 2,4-dichlororobenzoylvalerolactam, terephthaloyldivalerolactam, 4-Nitrobenzoylcaprolactam, 4-nitrobeazoylvalerolactam, and mixtures thereof.

Suitable imidazoles include N-benzoylimidazole and N-benzoylbenzimidazole, and other useful N-acyl group-containing peroxyacid precursors include N-benzoylpyrrolidone, dibenzoyltauric and benzoylpyroglutamic acid.

Another preferred class of peroxyacid bleach activator compounds are the amide-substituted compounds of the following general formulas:

wherein R¹ is an alkyl, aryl or alkaryl group having 1 to 14 carbon atoms, R² is an alkylene, arylene and alkarylene group having 1 to 14 carbon atoms and R⁵ is H or an alkyl, aryl or alkaryl group having 1 to 10 carbon atoms and L can be essentially any leaving group. R¹ preferably contains 6 to 12 carbon atoms. R² preferably contains 4 to 8 carbon atoms. R¹ can be straight chain or branched chain alkyl, substituted aryl or alkylaryl containing branching, substitution or both and can be derived from either synthetic sources or natural sources including, for example, talc fat. Analogous structural variations are permissible for R². The substitution can be alkyl, aryl, halogen, nitrogen, sulfur and other typical substituent groups or organic compounds. R⁵ is preferably H or methyl. R¹ and R⁵ should not contain more than 18 carbon atoms in total. Amide-substituted bleach activator compounds of this type are described in EP-A-0 170 386.

The L group must be sufficiently reactive for the reaction to occur within the optimal time frame (e.g., a wash cycle). Conversely, if L is too reactive, this activator will be difficult to stabilize for use in a bleach composition. These characteristics are generally concurrent with the pKa of the conjugate acid of the leaving group, although exceptions to this convention are known. Typically, leaving groups that exhibit such behavior are those where their conjugate acid has a pKa in the range of about 4 to about 13, preferably from about 6 to about 11, and most preferably from about 8 to about 11.

Preferred bleach precursors are those in which R¹, R² and R⁵ are as defined for the amide substituted compounds, L is selected from the group consisting of:

and mixtures thereof, wherein R¹ is an alkyl, aryl or alkaryl group having 1 to about 14 carbon atoms, R³ is an alkyl chain having 1 to 8 carbon atoms, R⁴ is H or R³ and Y is H or a solubilizing group.

The preferred solubilizing groups are -SO₃⁻M⁺, -CO₂⁻M⁺, -SO₄⁻M+, -N⁺(R₃)₄X⁻ and O< -N(R₃)₃ and most preferably -SO₃⁻M⁺ and -CO₂⁻M⁺, where R₃ is an alkyl chain having 1 to 4 carbon atoms, M is a cation which imparts solubility to the bleach activator and X is an anion which imparts solubility to the bleach activator. Preferably, M is an alkali metal, ammonium or substituted ammonium cation, with sodium and potassium being most preferred, and X is a halide, hydroxide, methyl sulfate or acetate anion. It should be noted that bleach activators having a leaving group which does not contain solubilizing groups should be well dispersed in the bleach solution to aid its dissolution.

Other preferred precursor compounds include those of the benzoxazine type having the formula:

including substituted benzoxazines of the type

wherein R¹ is H, alkyl, alkaryl, aryl, arylalkyl and wherein R², R³, R⁴ and R⁵ may be the same or different substituents selected from H, halogen, alkyl, alkenyl, aryl, hydroxyl, alkoxyl, amino, alkylamino, COOR₆ (wherein R⁵ is H or an alkyl group and carbonyl functions.

A particularly preferred precursor of the benzoxazine type is:

The peroxyacid bleach precursors are normally incorporated at a level of from 1 to 20%, more preferably from 2 to 10%, most preferably from 3 to 5%, by weight of the compositions.

Organic peroxyacids

The compositions may also contain organic peroxyacids, typically in a proportion of from 1 to 15%, more preferably from 1 to 10% by weight of the composition.

A preferred class of organic peroxyacid compounds are the amide-substituted compounds of the following general formulas:

wherein R¹ is an alkyl, aryl or alkaryl group having 1 to 14 carbon atoms, R² is an alkylene, arylene or alkarylene group having 1 to 14 carbon atoms and R⁵ is H or an alkyl, aryl or alkaryl group having 1 to 10 carbon atoms. R¹ preferably contains 6 to 12 carbon atoms. R² preferably contains 4 to 8 carbon atoms. R¹ can be straight or branched chain alkyl, substituted aryl or alkylaryl, containing branching, substitution or both and can be derived from either synthetic sources or natural sources including, for example, tallow fat. Analogous structural variations are permissible for R². Substitution may include alkyl, aryl, halogen, nitrogen, sulfur and other typical substituent groups or organic compounds. R5 is preferably H or methyl. PF and R5 should not contain more than 18 carbon atoms in total. Amide-substituted organic peroxyacid compounds of this type are described in EP-A-0 170 386.

Other organic peroxyacids include diperoxydodecanedioic acid, diperoxytetradecanedioic acid, diperoxyhexandecanedioic acid, mono- and diperazelaic acid, mono- and diperbrassylic acid, monoperoxyphthalic acid and its magnesium salt, perbenzoic acid and its salts, as described for example in EP-A-0 341 947.

Total available oxygen (AvO) fraction

It has been found that for optimum silver anti-tarnishing performance, the level of available oxygen in the present compositions, measured in units based on the weight percent of the composition, should be carefully controlled, and thus the level of available oxygen should be in the range of from 0.3% to 2.5%, preferably from 0.5% to 1.7%, more preferably from 0.6% to 1.2%, most preferably from 0.7% to 1.1%, measured by the method described below.

Rate of release of AvO

The rate of release of available oxygen is preferably also controlled; the rate of release of available oxygen from the compositions described herein should preferably be such that, when the method described below is used, the available oxygen is not completely released from the composition until 3.5 minutes, preferably the available oxygen is released in a time interval of from 3.5 minutes to 10.0 minutes, more preferably from 4.0 minutes to 9.0 minutes, most preferably from 5.0 to 8.5 minutes.

Method for measuring the level of total available oxygen (AvO) and the rate of release of AvO in a detergent composition Proceedings

1. A beaker of water (typically 2 liters) is placed on a stirrer hotplate and the stirring speed is selected to ensure that the product is evenly distributed in the solution.

2. The bleach composition (typically 8-g product sampled from a bulk stock using a Pascal sampler) is added and simultaneously a stop watch is started.

3. The temperature control should be set to maintain a constant temperature of 20ºC throughout the experiment.

4. Samples are taken from the bleach solution at 2 minute intervals for 20 minutes, beginning after 1 minute, and are titrated by the "Titration Procedure" as described below to determine the amount of available oxygen at each point.

Titration procedure

1. Add an aliquot of the bleach solution (above) and 2ml of sulfuric acid to a stirred beaker.

2. Approximately 0.2 g of ammonium molybdate catalyst (tetrahydrofuran form) is added.

3. 3 ml of 10% sodium iodide solution is added;

4. Titration with sodium thiosulfate is continued until the endpoint is reached. The endpoint can be determined using one of two methods. The first method is simply to watch the yellow iodine color fade until it is clear. The second and preferred method is to add soluble starch as the yellow color fades, turning the solution blue. More thiosulfate is added until the endpoint is reached (blue starch complex is decolorized).

The amount of AvO, measured in units of weight percent of available oxygen, for the sample at each time interval corresponds to the amount of titer according to the following equation:

The AvO fraction is plotted against time as follows:

Rate of release of organic peroxyacid

Where the composition contains a source of organic peroxyacid, the rate of release of the organic peroxyacid species is also preferably controlled. The kinetics of release into a wash solution are preferably such that in the T50 test method described herein, the time to reach a concentration containing 50% of the final concentration of the peroxyacid bleach is 180 seconds to 480 seconds, more preferably 200 seconds to 400 seconds, most preferably 240 seconds to 360 seconds.

Organic peroxyacid release rate - test method

The controlled release kinetics of the organic peroxyacid described herein are defined in terms of a 'T50 test method' which measures the time to reach 50% of the final concentration/proportion of the organic peroxyacid when a composition containing organic peroxyacid is dissolved according to the standard conditions now set forth.

The standard conditions involve a 1 liter glass beaker filled with 1000 ml of distilled water at 20ºC, to which 10 g of the composition is added. The contents of the beaker are stirred using a magnetic stirrer at 100 rpm. The final concentration/level is considered to be the maximum amount of organic peroxyacid concentration/level obtained after adding the composition to a beaker filled with water.

Appropriate analytical procedures are chosen to enable reliable determination of the random and final concentrations in solution of the organic peroxyacid following addition of the composition to the water in the beaker.

Such analytical methods may include those involving continuous monitoring of the proportion of the concentration of the component, including, for example, photometric and conductometric methods.

Alternatively, methods that involve removing titres from the solution at fixed time intervals, interrupting the dissolution process by an appropriate method, such as rapidly lowering the temperature of the titre and then determining the concentration of the component in the titre by any method, such as chemical titration methods.

Appropriate graphical techniques, including curve fitting techniques, may be used where appropriate to enable the calculation of the TA value from the raw analytical results.

The specific analytical method chosen to determine the concentration of the organic peroxyacid component depends on the nature of the component and on the nature of the composition containing this component.

Methods for regulating the release rate

A method for regulating the rate of release of AvO or organic peroxyacid into the wash solution may be provided.

Methods for regulating the rate of release of organic peroxyacid may provide for the regulated release of the peroxyacid bleach source itself into the wash solution. Alternatively, the method may comprise a method for inhibiting or preventing the in situ perhydrolysis reaction which releases the peroxyacid into the solution. Such methods could include, for example, regulating the release of the hydrogen peroxide source into the wash solution, for example by regulating the release of inorganic perhydrate salt acting as a hydrogen peroxide source into the wash solution.

Suitable methods for controlling release may include coating a suitable component with a coating designed to provide controlled release. The coating may therefore, for example, comprise a poorly water-soluble material or may be a coating of sufficient thickness that the kinetics of dissolution of the thick coating provide the controlled release rate.

The coating material can be applied using various methods. Any coating material is typically present in a weight ratio of coating material to bleaching agent of 1:99 to 1:2, preferably 1:49 to 1:9.

Suitable coating materials include triglycerides (e.g. partially hydrogenated vegetable oil, soybean oil, cottonseed oil), mono- or diglycerides, microcrystalline waxes, gelatin, cellulose, fatty acids and any mixtures thereof.

Other suitable coating materials may include the alkali and alkaline earth metal sulfates, silicates and carbonates, including calcium carbonate and silicas.

Preferred coating material is sodium silicate having a SiO2:Na2O ratio of 1.6:1 to 3.4:1, preferably 2.2:1 to 2.8:1, applied as an aqueous solution to give a level of 2% to 10% (normally 3% to 5%) of silicate solids based on the weight of the percarbonate. Magnesium silicate may also be included in the coating.

Any inorganic salt coating materials can be combined with organic binder materials to form composite coatings of inorganic Suitable binders include the C₁₀-C₂₀ alcohol ethoxylates containing 5-100 moles of ethylene oxide per mole of alcohol and more preferably the C₁₅-C₂₀ primary alcohol ethoxylates containing 20-100 moles of ethylene oxide per mole of alcohol.

Other preferred binders include certain polymeric materials. Polyvinylpyrrolidones having an average molecular weight of 12,000 to 700,000 and polyethylene glycols (PEG) having an average molecular weight of 600 to 5 · 10⁶, preferably 1,000 to 400,000, most preferably 1,000 to 10,000 are examples of such polymeric materials. Copolymers of maleic anhydride with ethylene, methyl vinyl ether or methacrylic acid, wherein the maleic anhydride constitutes at least 20 mole percent of the polymer, are other examples of polymeric materials useful as binders. These polymeric materials can be used as such or in combination with solvents such as water, propylene glycol and the above-mentioned C₁₀₋₂₀ alcohol ethoxylates containing 5-100 mole % ethylene oxide per mole. Other examples of binders include the C₁₀₋₂₀ mono- and diglycerol ethers and also the C₁₀₋₂ fatty acids.

Cellulose derivatives such as methylcellulose, carboxymethylcellulose and hydroxyethylcellulose, and homo- or copolymeric polycarboxylic acids or their salts are other examples of binders suitable for use herein.

One method of applying the coating material involves agglomeration. Preferred agglomeration methods include the use of any of the organic binder materials described above. Any conventional agglomerator/mixer may be used, including, but not limited to, pan, rotary drum type, and vertical mixer types. Molten coating compositions may also be applied by either pouring or spray atomization onto a moving bed of bleach.

Other methods for providing the required controlled release include mechanical devices for altering the physical characteristics of the bleach to regulate its solubility and release rate. Suitable protocols could include compaction, mechanical injection, manual injection and adjusting the solubility of the bleach compound by selecting the particle size of each particle component.

While the choice of particle size depends on both the composition of the particle component and the desire to meet the desired controlled release kinetics, it is desirable that the particle size should be higher than 500 micrometers, preferably having a mean particle diameter of 800 to 1200 micrometers.

Further protocols for providing controlled release methods include the appropriate choice of other components of the composition matrix such that, in the case where the composition is introduced into the wash solution, the The ionic strength environment provided therein enables the required kinetics for controlled release to be achieved.

Paraffin oil

The present compositions contain from 0.05% to 2.5%, preferably from 0.1% to 0.6%, by weight of the total composition, of a paraffin oil, typically a predominantly branched aliphatic hydrocarbon having a number of carbon atoms in the range of from 20 to 50; preferred paraffin oil selected from predominantly branched C25-4s species having a ratio of cyclic to non-cyclic hydrocarbons of from 1:10 to 2:1, preferably from 1:5 to 1:1. A paraffin oil meeting these characteristics having a ratio of cyclic to non-cyclic hydrocarbons of about 32:68 is sold by Wintershall, Salzbergen, Germany, under the trade name WINOG 70.

Benzotriazole compound

The compositions of the invention contain as an essential component a benzotriazole compound in a proportion of 0.005% to 3%, preferably 0.02% to 1%, and most preferably 0.05% to 0.5% of benzotriazole compound. Benzotriazole compound means a compound of the formula

which is benzotriazole and any derivatives thereof.

Derivatives of benzotriazole include those where the available substitution sites of the aromatic ring are fully or partially substituted. Substituents may include, for example, straight chain or branched chain alkyl groups containing, for example, 1 to 20 carbon atoms in the alkyl chain. Other substituents may include -OH, -SH, phenyl or halogen groups. Other derivatives include bisbenzotriazoles. British Patent GB-A-1 065 995 describes suitable substituted benzotriazoles of the formula

wherein R is a straight or branched chain alkyl group having 2 to 20 atoms, and a process for preparing such compounds. British Patent GB-A- 1 226 100 describes compositions containing 4,5,6,7-tetrahydrobenzotriazole compounds which are also suitable for inclusion in the compositions of the invention.

The British Patent GB-A-1 180 437 describes suitable bisbenzotriazoles of the formula:

wherein X represents a straight chain alkylene group having 1 to 6 carbon atoms in the chain, which is substituted with 1 or 2 alkyl groups having 1 to 4 carbon atoms, where the alkylene group contains only 1 carbon atom, or which is substituted with 1 or more alkyl groups having 1 to 4 carbon atoms, where the alkylene group contains 2 or more carbon atoms, or which is unsubstituted where the alkylene group contains 2 or more carbon atoms; a 1:1 cycloalkyl radical having at least 5 carbon atoms; a carbonyl group; a sulphuryl group, an oxygen atom; or a sulphur atom.

The compositions of the invention may further contain detergent compositions such as detergent builder compounds, surfactants, heavy metal ion complexing agents, enzymes, lime soap dispersants, foam control agents and mixtures thereof.

Builders

A highly preferred component of the detergent compositions in accordance with the invention is a detergent builder compound, preferably present at a level of from 1 to 80%, more preferably from 10 to 70%, most preferably from 20 to 60% by weight of the composition.

The proportion of alkali metal carbonate or bicarbonate in the present compositions should preferably be less than 7% by weight, preferably less than 5% by weight, based on the total composition. Most preferably, the present composition should be free of alkali metal carbonate or bicarbonate species.

Suitable detergent builder compounds include, but are not limited to, monomeric polycarboxylates, or their acid forms homo- or copolymeric polycarboxylic acids or their salts, in which the polycarboxylic acid comprises at least two carboxylic acid residues separated by no more than two carbon atoms, carbonates, bicarbonates, borates, phosphates, silicates, and mixtures of any of the foregoing. Suitable monomeric or oligomeric carboxylate builders can be selected from a wide range of compounds, but preferably such compounds have a first log carboxyl acidity constant (pK1) of less than 9, preferably between 2 and 8.5, more preferably between 4 and 7.5.

The logarithmic acidity constant is related to the equilibrium

H+ + A&supmin; ä--åHA

where A is the fully ionized carboxylate anion of the builder salt. The equilibrium constant for dilute solutions is therefore given by the expression

and pK₁ = log₁₀K₁.

For the purposes of this specification, acidity constants are defined at 25ºC and at zero ionic strength. Literature values are used as far as possible (see "Stability Constants of Metal-Ion Complexes", Special Publication No. 25, The Chemical Socie London): where there is doubt, these are determined by potentiometric titration using a glass electrode.

The carboxylate or polycarboxylate builder may be of the monomeric or oligomeric type, although monomeric polycarboxylates are generally preferred for reasons of cost and performance.

Monomeric and oligomeric builders can consist of acyclic, alicyclic, heterocyclic and aromatic carboxylates of the general formulas:

or

wherein R¹ is H, C₁₋₃�0 alkyl or alkenyl, optionally substituted by hydroxy, carboxy, sulfo or phosphono groups or bonded to a polyethyleneoxy radical having up to 20 ethyleneoxy groups; R² is H, C₁₋₄ alkyl, alkenyl or hydroxyalkyl or alkaryl, sulfo or phosphono groups;

X represents a single bond; O; S, SO; SO₂; or NR₁;

Y is H; carboxyl; hydroxy; carboxymethyloxy; or C₁₋₃₀ alkyl or alkenyl, optionally substituted by hydroxy or carboxy groups;

Z is H; or carboxy;

m is an integer from 1 to 10;

n is an integer from 3 to 6;

p, q are integers from 0 to 6, where p + q is 1 to 6; and where X, Y and Z each have the same or different representations when repeated in a particular molecular formula, and where at least one Y or Z in a molecule contains a carboxyl group.

Suitable carboxylates containing one carboxy group include the water-soluble salts of lactic acid, glycolic acid and ether derivatives thereof as described in Belgian Patent Nos. 831,368, 821,369 and 821,370. Polycarboxylates containing two carboxy groups include the water-soluble salts of succinic acid, malonic acid, (ethylenedioxy)diacetic acid, maleic acid, diglycolic acid, tartaric acid, tartronic acid and fumaric acid, as well as the ether carboxylates described in German Offenlegungsschrift 2,446,686 and 2,446,687 and US Patent No. 3,935,257 and the sulphyl carboxylates described in Belgian Patent No. 840,623. Polycarboxylates having three carboxy groups include in particular water-soluble citrates, aconitrates and citracenates, as well as succinate derivatives such as the carboxymethyloxysuccinates described in British Patent No. 1,379,241, lactooxysuccinates described in British Patent No. 1,389,732 and aminosuccinates described in Dutch Application 7,205,873 and the oxypolycarboxylate materials such as 2-oxa-1,1,3-propane-tricarboxylate described in British Patent No. 1,387,447.

Polycarboxylates containing four carboxy groups include the oxydisuccinates, 1,1,2,2-ethanetetracarboxylates, 1,1,3,3-propanetetracarboxylates and 1,1,2,3-propanetetracarboxylates described in British Patent No. 1,261,829. Polycarboxylates containing sulfo substituents include the sulfosuccinate derivatives described in British Patent Nos. 1,398,421 and 1,398,422 and in U.S. Patent No. 3,936,448 and the sulfonated pyrolyzed citrates described in British Patent No. 1,439,000.

Alicyclic and heterocyclic polycarboxylates include cyclopentane-cis,cis,cistetracarboxylate, cyclopentadiene pentacarboxylate, 2,3,4,5-tetrahydrofuran-cis,cis,cis-tetracarboxylate, 2,5-tetrahydrofuran-cis-dicarboxylates, 2,2,5,5-tetrahydrofuran-tetracarboxylates, 1,2,3,4,5,6-hexane-hexacarboxylates and carboxymethyl derivatives of polyhydric alcohols such as sorbitol, mannitol and xylitol. Aromatic polycarboxylates include mellitic acid, pyromellitic acid and the phthalic acid derivatives as described in British Patent No. 1,425,343.

Of the above, the preferred polycarboxylates are hydroxycarboxylates containing up to three carboxy groups per molecule, especially citrates.

The parent acids of the monomeric or oligomeric polycarboxylate chelating agents or mixtures thereof with their salts, e.g. citric acid or citrate/citric acid mixtures, are also contemplated as components of builder systems of detergent compositions according to the present invention.

Other suitable water-soluble organic salts are the homo- or copolymeric polycarboxylic acids or their salts, the polycarboxylic acid comprising at least two carboxyl radicals separated by not more than two carbon atoms. Polymers of the latter type are described in GB-A-1 596 756. Examples of such salts are polyacrylates having a MW of 2000-5000 and their copolymers with maleic anhydride, such as copolymers having a molecular weight of 20,000 to 70,000, especially about 40,000. These materials are normally used in proportions of from 0.5 to 10% by weight, more preferably from 0.75 to 8% by weight, most preferably from 1 to 6% by weight of the composition.

Water-soluble detergent builders include, but are not limited to, the alkali metal, ammonium and alkanolammonium salts of polyphosphates (exemplified by the tripolyphosphates, pyrophosphates and glassy polymeric metaphosphates), phytic acid, silicates, carbonates (including bicarbonates and sesquicarbonates) and sulfates. However, the levels of incorporation of carbonates or bicarbonates or mixtures thereof is limited to less than 7% by weight of the composition.

Borate builders, as well as builders containing borate-forming materials that can form borate under detergent storage or wash conditions, may also be used, but are not preferred at wash conditions of less than about 50°C, especially less than about 40°C.

Specific examples of phosphate builders are the alkali metal tripolyphosphates, sodium, potassium and ammonium pyrophosphate, sodium and potassium orthophosphate, sodium polymetal phosphate, in which the degree of polymerization is in the range of about 6 to 21, and salts of phytic acid.

Suitable silicates include the water soluble sodium silicates having a SiO2:Na2O ratio of 1.0 to 2.8, with ratios of 1.6 to 2.4 being preferred and a ratio of 2.0 being most preferred. The silicates may be in the form of either the anhydrous salt or a hydrated salt. Sodium silicate having a SiO2:Na2O ratio of 2.0 is the most preferred silicate.

Silicates are preferably present in the automatic dishwashing detergent compositions of the invention at a level of from 5 to 50% by weight of the composition, more preferably from 10 to 40% by weight, most preferably from 12 to 25% by weight.

Examples of such less water-soluble builders include the crystalline layered silicates and the largely water-insoluble sodium aluminosilicates.

Crystalline sodium layer silicates have the formula:

NaMSixOx+1.yH₂O

wherein M is sodium or hydrogen, x is a number from 1.9 to 4 and y is a number from 0 to 20. Crystalline sodium layered silicates of this type are described in EP-A-0 164 514 and processes for their preparation are described in DE-A-34 17 649 and DE-A-37 42 043. For the purpose of the present invention, x in the general formula above has a value of 2, 3 or 4 and is preferably 2. More preferably M is sodium and y is 0 and preferred examples of this formula include the α-, β-, γ- and δ-forms of Na₂Si₂O₅. These materials are available from Hoechst AG FRG as NaSKS-5, NaSKS-7, NaSKS-11 and NaSKS-6 respectively. The most preferred material is δ- Na₂Si₂O₅, NaSKS-6.

The crystalline layered sodium silicate material is preferably present in granular detergent compositions as particles in intimate admixture with a solid, water-soluble, ionizable material. The solid, water-soluble, ionizable material is selected from organic acids, organic and inorganic acid salts and mixtures thereof. The main requirement is that the material should contain at least one functional acid group whose pKa should be less than 9, thereby providing the possibility for at least partial neutralization of the hydroxyl ions released by the crystalline layered silicate.

The incorporation into the particles of other components in addition to the crystalline layered silicate and the ionizable, water-soluble compound may be advantageous particularly in processing the particles and also in increasing the stability of detergent compositions in which the particles are included. In particular, certain types of agglomerates may require the addition of one or more binders to assist in binding the silicate and ionizable, water-soluble material so as to produce particles with acceptable physical properties.

The particles containing crystalline layered sodium silicate may have a variety of physical forms such as extrudates, marumes, agglomerates, flakes or compacted granules. A preferred process for producing compacted granules comprising crystalline layered silicate and a solid, water-soluble, ionizable material has been described in jointly granted British Application No. 9 108 639.7, filed April 23, 1991.

Suitable aluminosilicate zeolites have the unit cell formula Naz[(AlO₂)z(SiO₂)y] xH₂O, where z and y are at least 6; the molar ratio of z to y is 1.0 to 0.5 and x at least 5, preferably 7.5 to 276, more preferably 10 to 264. The aluminosilicate material is in hydrated form and is preferably crystalline and contains 10% to 28%, more preferably 18% to 22% water in bound form.

The above aluminosilicate ion exchange materials are further characterized by a particle size diameter of 0.1 to 10 micrometers, preferably 0.2 to 4 micrometers. The term "particle size diameter" as used herein means the average particle diameter of a particular ion exchange material as determined by conventional analytical techniques, such as microscopic determination using a scanning electron microscope or by means of a laser granulometer. The aluminosilicate ion exchange materials are further characterized by their calcium ion exchange capacity, which is at least 200 mg equivalent CaCO3 water hardness/g aluminosilicate, calculated on an anhydrous basis, and which is generally in the range of 300 mg-eq/g to 352 mg-eq/g. The aluminosilicate ion exchange materials herein are further characterized by their calcium ion exchange rate which is at least 130 mg-eq CaCO3/liter/min/(g/liter) [2 grains Ca++/gallon/min/(grams/gallon)] aluminosilicate (anhydrous basis) and which is generally within a range of 130 mg-eq CaCO3/liter/min/(grams/liter) [2 grains/gallon/min/(grams/gallon)] to 390 mg-eq CaCO3/liter/min (grams/liter) [4 grains/gallon/min/(grams/gallon)] based on calcium ion hardness.

Optimum aluminosilicates for builder purposes exhibit a calcium ion exchange rate of at least 260 mg-eq CaCO3/liter/min/(grams/liter) [4 grains/gallon/min (grams/gallon)].

The aluminosilicate ion exchange materials may be naturally occurring materials, but are preferably synthetically derived. A process for producing aluminosilicate ion exchange materials is described in U.S. Patent No. 3,985,669. Synthetic crystalline aluminosilicate ion exchange materials are available under the names zeolite A, zeolite B, zeolite P, zeolite X, zeolite HS, and mixtures thereof. Zeolite A has the formula:

Na12[(AlO2)12(SiO2)12].XH2O

wherein x is 20 to 30, especially 27. Zeolite X has the formula Na₈₆[(AlO₂)₈₆(SiO₂)₁₀₆].276 H₂O has the formula Na₆[(AlO₂)₆(SiO₂)₆] 7.5 H₂O.

The heavy metal ion complexing agent

In a preferred aspect, the cleaning compositions further contain narrowly defined proportions of a heavy metal ion complexing agent, such proportions being in a range of 0.005 to 3%, preferably 0.01 to 1%, most preferably 0.05 to 0.8% by weight of the total composition.

Suitable heavy metal ion complexing agents for use herein include organic phosphonates such as aminoalkylene poly(alkylene phosphonate), alkali metal ethane-1-hydroxydiphosphonates, nitrilotrimethylene phosphonates.

Preferably under The above species are diethylenetriamine penta(methylenephosphonate), hexamethylenediamine tetra(methylenephosphonate) and hydroxyethylene-1,1-diphosphonate.

The phosphonate compounds can be present either in their acid form or as a complex of either an alkali or alkali metal ion, the molar ratio of the metal ions to the phosphonate compound being at least 1:1. Such complexes are described in US-A-4,259,200. Preferably, the phosphonate compounds are present in the form of their magnesium salt.

Other suitable complexing agents for inclusion in the compositions of the invention include nitrilotriacetic acid and polyaminocarboxylic acids such as ethylenediaminetetraacetic acid, ethylenetriaminepentaacetic acid, ethylenediaminedisuccinic acid or the water-soluble alkali metal salts thereof. Particularly preferred is ethylenediamine-N,N'-disuccinic acid (EDDS) or the alkali metal, alkaline earth metal, ammonium or substituted ammonium salts thereof or mixtures thereof. Preferred EDDS compounds are the free acid form and the sodium or magnesium salt or complex thereof. Examples of such preferred sodium salts of EDDS include Na₂EDDS and Na₃EDDS. Examples of such preferred magnesium complexes of EDDS include MgEDDS and Mg₂EDDS. The magnesium complexes are most preferred for inclusion in the compositions of the invention.

Still further suitable complexing agents for use herein are iminodiacetic acid derivatives such as 2-hydroxyethyldiacetic acid or glyceryl iminodiacetic acid, as described in EP-A-317 542 and EP-A-399 133.

The heavy metal ion complexing agent described herein may consist of a mixture of the species described above.

Optional chlorine bleach components

Chlorine bleaches include the alkali metal hypochlorites and chlorinated cyanuric acid salts. The use of chlorine bleaches in the composition of the invention is optional and preferably minimized, and more preferably the present compositions do not contain chlorine bleach.

Surfactant

A highly preferred component of the compositions of the invention is a surfactant system comprising the surfactant selected from anionic, cationic, nonionic, ampholytic and zwitterionic surfactants and mixtures thereof. The surfactant system is preferably present at a level of from 0.5 to 30%, more preferably 1 to 25%, most preferably 2 to 20% by weight of the compositions.

A typical listing of anionic, nonionic, ampholytic and zwitterionic classes and species of these classes is given in U.S. Patent 3,929,678, issued to Laughlin and Heuring on Dec. 30, 1975. A listing of suitable cationic surfactants is given in U.S. Patent 4,259,217, issued to Murphy on March 31, 1981.

A list of surfactants typically included in automatic dishwashing detergent compositions is given in EP-A-0 414 549.

Sulfonate and sulfate surfactants are useful herein. Sulfonates include alkylbenzene sulfonates having 5 to 15 carbon atoms in the alkyl moiety and alpha-sulfonated methyl fatty acid esters in which the fatty acid is derived from a C6-C18 fatty source. Preferred sulfate surfactants are alkyl sulfates having 6 to 16, preferably 6 to 10 carbon atoms in the alkyl moiety.

A useful surfactant system comprises a mixture of two alkyl sulfate materials, their respective average chain lengths differing from each other. The cation in each case is again an alkali metal, preferably sodium. The alkyl sulfate salts can be derived from natural or synthetic hydrocarbon sources.

The C6-C16 alkyl ethoxysulfate salt comprises a primary alkyl ethoxysulfate derived from the condensation product of a C6-C16 alcohol condensed with an average of 1 to 7 ethylene oxide groups, per mole.

Preferred are the C6-C16-alkyl ethoxy sulfate salts having on average one to five ethoxy groups per mole.

Other anionic surfactants suitable for the purposes of the invention are the alkali metal sarcosinates of the formula

R-CON(R¹)CH₂COOM

wherein R is a linear C₅-C₁₇ or branched alkyl or alkenyl group, R¹ is a C₁-C₄ alkyl group and M is an alkali metal ion. Preferred examples are the lauroyl, cocoyl (C₁₂-C₁₄), myristyl and oleylmethyl sarcosinates in the form of their sodium salts.

Another class of anionic surfactants useful herein are the alkyl ester sulfonate surfactants which include linear esters of C8-C20 carboxylic acids (i.e. fatty acids) which are sulfonated with gaseous SO3 according to "The Journal of the American Oil Chemists Society", 52 (1975), pages 323-329. Suitable starting materials would include natural fatty substances such as derived from tallow, palm oil.

The preferred alkyl ester sulfonate surfactants have the structural formula:

wherein R3 is C8-C20 hydrocarbyl, preferably alkyl, or a combination thereof, R4 is C1-C6 hydrocarbyl, preferably alkyl, or a combination thereof, and M is a cation which forms a water-soluble salt with the alkyl ester sulfonate. Suitable salt-forming cations include metals such as sodium, potassium and lithium, and substituted or unsubstituted ammonium cations such as monoethanolamine, diethanolamine and triethanolamine. Preferably R3 is C10-C16 alkyl, and R4 is methyl, ethyl or isopropyl. Particularly preferred are the methyl ester sulfonates in which R3 is C10-C16 alkyl.

A preferred class of nonionic surfactants useful in the present invention includes the water-soluble C6-C16 ethoxylated fatty alcohols and the mixed C6-C16 ethoxylated/propoxylated fatty alcohols and mixtures thereof. Preferably, the ethoxylated fatty alcohols are the ethoxylated C₁₀-C₁₆ fatty alcohols with a degree of ethoxylation of 3 to 50, most preferably these are the ethoxylated C₁₂-C₁₆ fatty alcohols with a degree of ethoxylation of 3 to 40. Preferably, the mixed ethoxylated/propoxylated fatty alcohols have an alkyl chain length of 10 to 16 carbon atoms, a degree of ethoxylation of 3 to 30 and a degree of propoxylation of 1 to 10.

Thus, C6-C16 alcohol itself can be obtained from natural or synthetic sources. Thus, C6-C16 alcohols derived from natural fats or a Ziegler olefin buildup or OXO synthesis can form suitable sources for the alkyl group. Examples of synthetically derived materials include Dobanol 25 (RTM) sold by Shell Chemicals (UK) Ltd, which is a mixture of C12-C15 alcohols, Ethyl 24, sold by Ethyl Corporation, which is a mixture of C12-C15 alcohols, and a mixture of C13-cis alcohols, in a ratio of 67% C13, 33% C15, sold under the trade name Lutensol by BASF GmbH, and Synperonic (RTM) by ICI Ltd., and Lial 125, sold by Liquichimica Italiana. Examples of naturally occurring materials from which the alcohols can be derived are coconut oil and palm kernel oil and the corresponding fatty acids.

Another class of non-ionic surfactants includes alkylpolyglucoside compounds of the general formula

RO(CnH₂nO)tZx

wherein Z is a residue derived from glucose; R is a saturated hydrophobic alkyl group containing 6 to 16 carbon atoms, preferably 6 to 14 carbon atoms; t is 0 to 10 and n is 2 or 3; · is 1, 1 to 4, the compounds including less than 10% unreacted fatty alcohol and less than 50% short chain alkyl polyglucosides. Compounds of this type and their use in detergent compositions are described in EP-B-0 070 074, 0 070 077, 0 075 996 and 0 094 118.

Another preferred nonionic surfactant is a polyhydroxy fatty acid amide surfactant compound of the structural formula:

wherein R¹ is H, C₁-C₄ hydroxycarbyl, 2-hydroxyethyl, 2-hydroxypropyl, or a mixture thereof, preferably C₁-C₄ alkyl, more preferably C₁ or C₂ alkyl, most preferably C₁ alkyl (i.e. methyl); and R² is C₅-C₁₅ hydrocarbyl, preferably straight chain C₅-C₁₃ alkyl or alkenyl, more preferably straight chain C₅-C₁₁ alkyl or alkenyl, most preferably straight chain C₅-C₉ alkyl or alkenyl, or a mixture thereof; and Z is a polyhydroxyhydrocarbyl having a linear hydrocarbyl chain with at least 3 hydroxyls directly linked to the chain or an alkoxylated derivative (preferably ethoxylated or propoxylated) thereof. Z is preferably derived from a reducing sugar in a reductive amination reaction; more preferably Z is glycityl. Suitable reducing sugars include glucose, fructose, maltose, lactose, galactose, mannose and xylose. Raw materials may include high dextrose corn syrup, high fructose corn syrup and high maltose corn syrup, as well as the individual sugars listed above. These corn syrups may provide a mixture of sugar components for Z. It should be understood that this is in no way intended to exclude other suitable raw materials. Z is preferably selected from the group consisting of -CH₂-(CHOH)n-CH₂OH, -CH(CH₂OH)-(CHOH)n-1-CH₂OH, -CH₂-(CHOH)₂(CHOR')(CHOH)-CH₂OH, wherein n is an integer from 3 to 5 inclusive and R' is H or a cyclic or aliphatic monosaccharide and alkoxylated derivatives thereof. Most preferred are glycityls in which n is 4, especially -CH₂-(CHOH)₄-CH₂OH.

In formula (I), R¹ can be, for example, N-methyl, N-ethyl, N-propyl, N-isopropyl, N-butyl, N-2-hydroxyethyl or N-2-hydroxypropyl.

R²-CO-N- can be, for example, cocamide, stearamide, oleamide, lauramide, myristamide, capricamide, palmitamide or tallowamide.

Z can be 1-deoxyglucityl, 2-deoxyfrucittyl, 1-deoxymaltityl, 1-deoxylactityl, 1- deoxygalactityl or 1-deoxymannityl or 1-deoxymaltotriotityl. Preferred compounds are N-methyl-N-1-deoxyglucityl-C₁₄-Cis-fatty acid amides.

Another class of surfactants are the semipolar surfactants, such as amine oxides. Suitable amine oxides are selected from mono-C6-C20, preferably C6-C10-N-alkyl or alkenylamine oxides and propylene-1,3-diamine dioxides in which the remaining N-positions are substituted by methyl, hydroxyethyl or hydroxypropyl groups.

Cationic surfactants may also be used in the detergent compositions described herein and suitable quaternary ammonium surfactants are selected from mono-C6-C16, preferably C6-C10 N-alkyl or alkenyl ammonium surfactants in which remaining N-positions are substituted by methyl, hydroxyethyl or hydroxypropyl groups.

Enzymes

Another optional ingredient that is useful in detergent compositions is one or more enzymes.

Preferred enzymatic materials include amylases, neutral and alkaline proteases, lipases and esterases which are conventionally incorporated into detergent compositions. Suitable enzymes are illustrated in U.S. Patents 3,519,570 and 3,533,139.

Preferred commercially available protease enzymes include those sold under the trade names Alcalase and Savinase by Novo Industries A/S (Denmark) and Maxatase by International Bio-Synthetics, Inc. (Netherlands). Protease enzyme may be incorporated into the compositions of the invention at a level of from 0.005% to 2% active enzyme by weight of the composition.

Preferred amylases include, for example, α-amylases obtained from a specific strain of B licheniforms, more fully described in GB 1 269 839 (Novo). Preferred commercially available amylases include, for example, Rapidase, sold by International Bio-Synthetics Inc., and Termamyl, sold by Novo Industries A/S. The invention in a proportion of from 0.001% to 2% of active enzyme, based on the weight of the composition.

A preferred lipase is derived from Pseudomonas pseudoalcaligenes, which is described in the granted European patent EP-B-0 218 272.

Another preferred lipase described herein is obtained by cloning the gene from Humicola lanuginosa and expressing the gene in Aspergillus oryza as host, as described in European Patent Application EP-A-0 258 068, which is commercially available from Novo Industri, A/S. Bagsvaerd, Denmark, under the trade name Lipolase. This lipase is also described in U.S. Patent 4,810,414, Huge-Jensen et al., March 7, 1989.

Lime soap dispersant

A further ingredient is a lime soap dispersant compound which is present in an amount of 0.05 to 40%, more preferably 0.1 to 20%, most preferably 0.25 to 10% by weight of the compositions.

A lime soap dispersant is a material that prevents the precipitation of alkali metal, ammonium or amine salts of fatty acids by calcium or magnesium ions.

Preferred lime soap dispersants include ethoxylated C13-15 alcohol sulfates having an average degree of ethoxylation of 3.

Another optional component of the cleaning compositions according to the invention is a silicone foam control agent which is present in amounts of from 0.01 to 5% by weight, more preferably from 0.05 to 3% by weight, most preferably from 0.05 to 1% by weight of the composition.

Foam regulator

By silicone foam control agent is meant any foam control agent which comprises a silicone antifoam compound. Thus, silicone foam control agents include agents containing silicone-silica mixtures and particles in which the silicone or silicone-silica mixture is incorporated in a water-soluble or water-dispersible carrier material. Alternatively, the foam control agents may comprise silicone or silicone-silica dissolved or dispersed in a liquid carrier and applied by spraying onto one or more of the other components of the detergent composition.

In industrial practice, the term "silicone" has become a collective term, which includes a variety of polymers with a relatively high molecular weight, containing siloxane units and hydrocarbyl groups of various types.

In general, silicone antifoam compounds can be classified as siloxanes of the general structure:

where each R can independently be an alkyl or an aryl radical. Examples of such substituents are methyl, ethyl, propyl, isobutyl and phenyl. Preferred polydiorganosiloxanes are polydimethylsiloxanes having terminal trimethylsilyl units and having a viscosity at 25°C of 5 x 10-5 m2s-1 to 0.1 m2s-1, i.e. a value of n in the range of 40 to 1500. These are preferred due to their ready availability and their relatively low cost.

A preferred type of silicone foam control agent useful in the compositions described herein comprises a mixture of an alkylated siloxane of the type described above and solid silica.

The solid silica may be a fumed silica, a precipitated silica or a silica produced by the gelation technique. The suitable silica particles have an average particle size of from 0.1 to 50 micrometers, preferably from 1 to 20 micrometers and a surface area of at least 50 m²/g. These silica particles can be made hydrophobic by treating them with dialkylsilyl groups and/or trialkylsilyl groups which are either directly attached to the silica or by means of a silicone resin. It is preferred to use a silica whose particles have been made hydrophobic with dimethyl and/or trimethylsilyl groups. The foam control agents for inclusion in the detergent compositions according to the invention suitably contain an amount of silica such that the weight ratio of silica to silicone is in the range from 1:100 to 3:10, preferably from 1:50 to 1:7.

A preferred silicone foam control agent is represented by a hydrophobic silanated (most preferably trimethyl silanated) silica having a particle size in the range of 10 nanometers to 20 nanometers and a specific surface area of greater than 50 m²/g intimately mixed with a dimethyl silicone fluid having a molecular weight in the range of 500 to 200,000 at a weight ratio of silicone to silanated silica of 1:1 to 1:2.

Another preferred silicone foam control agent is described in Bartolotta et al., U.S. Patent 3,933,672. Other particularly useful foam suppressors are the self-emulsifying silicone foam suppressors described in German Patent Application DTOS 2 646 126, published April 28, 1977. An example of a One such compound is DC0544, commercially available from Dow Corning, which is a siloxane/glycol copolymer.

A highly preferred foam control agent is a particulate substance of the type described in EP-A-0 210 731 which comprises a silicone antifoam agent and an organic material having a melting point in the range 50° to 85°C, the organic material comprising a monoester of glycerol and a fatty acid having a carbon chain of 12 to 20 carbon atoms. EP-A-0 210 721 describes similar particulate foam control agents but in which the organic material is a fatty acid or alcohol having a carbon chain of 12 to 20 carbon atoms or a mixture thereof having a melting point of 45° to 80°C.

Other highly preferred silicone foam control agents are described in European application EP-0 49534 in the name of the Procter and Gamble Company which discloses granular foam control agents comprising a silicone antifoam compound, a carrier material, an organic coating material and glycerol in a weight ratio of glycerol:silicone antifoam compound of 1:2 to 3:1. European application EP 046169 describes highly preferred granular foam control agents comprising a silicone antifoam compound, a carrier material, an organic coating material and crystalline or amorphous aluminosilicate in a weight ratio of aluminosilicate:silicone antifoam compound of 1:3 to 3:1. The preferred carrier material in both of the highly preferred granular foam control agents described above is starch.

The preferred methods for incorporating the silicone foam control agents involve either applying the silicone foam control agent in liquid form by spraying it onto one or more of the major components of the composition or, alternatively, forming the silicone foam control agent into separate particles which can then be mixed with the other solid components of the composition. The inclusion of the foam control agents as separate particles also allows for the inclusion of other foam control agents therein, such as C20-C24 fatty acids, microcrystalline waxes and high molecular weight copolymers of ethylene oxide and propylene oxide, which would otherwise interfere with the dispersibility of the matrix. Techniques for forming such foam control particles are described in the aforementioned U.S. Patent No. 3,933,672 to Bartolotta et al.

Other optional ingredients suitable for inclusion in the compositions of the invention include antiredeposition and soil suspending agents, corrosion inhibitors, perfumes, colors and filler salts, with sodium sulfate being a preferred filler salt.

Form of compositions

The compositions of the invention may be formulated in any desired form, such as powders, granules, pastes, liquids, gels and tablets, with granular forms being preferred.

The bulk density of granular compositions according to the present invention is typically at least 650 g/liter, more usually at least 700 g/liter, and more preferably from 800 g/liter to 1200 g/liter.

Bulk density is measured using a simple funnel and cup device consisting of a conical funnel rigidly mounted on a base and fitted with a flap valve at its lower extremity to allow emptying of the contents into an axially aligned cylindrical cup positioned below the funnel. The funnel measures 130 mm and 40 mm at its upper and lower extremities respectively. It is mounted so that the lower extremity is 140 mm above the cup surface of the base. The cup has an overall height of 90 mm, an internal height of 87 mm and an internal diameter of 84 mm. Its nominal volume is 500 ml.

To take a measurement, the funnel is filled with powder by pouring it by hand, the flap valve is opened and powder is poured in until it overflows. The filled cup is removed from the frame and excess powder is removed from the cup by passing a smooth-edged tool, such as a knife, over its upper edge. The filled cup is then weighed and the value obtained for the weight of the powder is doubled to obtain the bulk density in g/litre. Repeat measurements are taken as required.

The particle size of the components of granular compositions according to the invention should preferably be such that not more than 5% of the particles are larger than 1.4 mm in diameter and not more than 5% of the particles are smaller than 0.15 mm in diameter.

Generally, if the detergent compositions are in liquid form, then the liquid should be thixotropic (i.e., exhibit a high viscosity when subjected to a low load and a lower viscosity when subjected to a high load), or at least have a very high viscosity, for example, 1,000 to 10,000,000 centipoise. In many cases, it is desirable to include a viscosity control agent or a thixotropic agent to provide a suitable liquid product form. Suitable thixotropic or viscosity control agents include methylcellulose, carboxymethylcellulose, starch, polyvinyl, pyrrolidone, gelatin, colloidal silica, and natural or synthetic clay minerals.

Paste compositions according to the invention generally have viscosities of about 5000 centipoise and up to several hundred million centipoise. To provide satisfactory paste compositions, a small amount of a solvent or solubilizing agent or a gelling agent may be included. Water is most commonly used in this context and forms the continuous phase of a concentrated dispersion. Certain nonionic surfactants in high proportions form a gel in the presence of a small amount of water and other solvents. Such gelled compositions are also contemplated in the present invention.

pH value of the compositions

The pH of a 1% solution of the present compositions is preferably 9.6 to 12, preferably 9.8 to 11.5, and most preferably 10.0 to 11.0.

Method of preparation of the compositions described herein

A preferred method of preparation for the compositions described herein comprises premixing the paraffin oil with a dispersant and spraying the resulting intimate premix onto the remainder of the composition. The dispersant may advantageously consist of a nonionic surfactant as described above, which therefore performs two functions in the present composition.

A preferred dispersant is Plurafac LF404, sold by BASF.

An alternative approach is to spray the intimate mixture of paraffin oil and dispersant onto the particles of a bleach, which results in a reduction in the dissolution rate of the bleach in water and thus provides for a regulation of the rate of release of available oxygen. The coated bleach particles are then dry-mixed with the rest of the composition.

In another process embodiment described herein, the bleach particles are compacted before being dry-blended with the remainder of the composition.

This technique slows down the dissolution rate in water and is therefore advantageously applied to otherwise rapidly dissolving species such as perborate monohydrate.

In this embodiment, the paraffin oil is typically compacted with the bleaching species, and optionally with other ingredients such as sodium sulfate and/or binder. The resulting particles are then dry-blended with the remainder of the ingredients.

Examples

The following examples illustrate the present invention.

For the cleaning agent compositions below, abbreviated names have the following meanings:

Citrate: Trisodium citrate dihydrate

Phosphate: Sodium tripolyphosphate

MA/AA: Copolymers of 1:4 maleic acid/acylic acid

Silicate: Amorphous sodium silicate (SiO₂: Na₂O ratio normally follows)

Protease: Proteolytic enzyme sold under the trade name Savinase by Novo Industries A/S

Amylase: Amylolytic enzyme, sold under the trade name Termamyl by Novo Industries A/S

Non-ionic substance: Mixed ethoxylated/propoxylated C₁₃-C₁₅ fatty alcohol with an average degree of ethoxylation of 3.8 and an average degree of propoxylation of 4.5, sold under the trade name Plurafac LF404 by BASF GmbH

Anionic substance: C₆₋₁₀-alkyl ethoxy sulfate with 1-5 ethoxy groups per mole

Sulfate: Anhydrous sodium sulfate

TAED: Tetraacetylethylenediamine

DTPMP: Diethylenetriaminepenta(methylenephosphoric acid)

EDDS: Ethylenediamine-N,N-disuccinic acid

Benzotriazole: Benzotriazole

The following machine dishwashing detergents according to the invention are prepared (parts by weight):

(1) Pre-compacted before installation

(2) WINOG 70 from Wintershall

(3) Premixed with the paraffin oil before introduction

(4) Lutensol AO12 from BASF

The following comparative tests were carried out; composition A according to the invention was compared with compositions B and C with respect to its silver tarnishing performance. Composition B does not contain paraffin oil or benzotriazole. Composition C contains paraffin but does not contain benzotriazole.

The test protocol applied includes machine tests using a Bosch-Siemens dishwasher, a 20 g product dosage, economy cycles at 65ºC and 20 cycles.

The performance was assessed by a panel of four experts through visual inspection according to the following scale, whereby:

0 = no tarnishing (shiny silver)

1 = very easy to start

2 = Start-up

3 = heavily tarnished

4 = very strong tarnishing (black coating).

The results were as follows:

Comparison A Comparison B Comparison C

Composition A exhibits superior silver anti-tarnishing properties over compositions B and C according to the invention.

Claims (11)

1. An automatic dishwashing detergent composition having bleachable stain removing and silver tarnishing preventing properties, comprising an oxygen releasing bleaching agent, the level of oxygen releasing agent being such that the level of available oxygen, measured by the method described herein, is from 0.3 to 2.5%; 0.05 to 2.5% by weight of a paraffin oil; and 0.005 to 3 wt.% of a benzotriazole compound. 2. The composition of claim 1, wherein the rate of release of available oxygen is such that the available oxygen is completely released from the composition in a time interval of 3.5 minutes to 10 minutes using the test protocol described in the present specification. 3. Composition according to claims 1-2, containing a source of organic peroxyacid, wherein according to the T50 test method described herein the time to achieve a concentration which is 50% of the final concentration of the peroxyacid is 180 seconds to 480 seconds. 4. Composition according to claims 1-3, wherein the paraffin oil is present in a proportion of 0.1 to 0.6%. 5. Composition according to claims 1-4, wherein the paraffin oil is selected from predominantly branched, aliphatic hydrocarbons having 20 to 50, preferably 25 to 45 carbon atoms, with a ratio of cyclic to non-cyclic hydrocarbons of 1:5 to 1:1. 6. Composition according to claims 1-5, wherein the benzotriazole compound is present in amounts of 0.02 to 1%. 7. Composition according to claims 1-6, wherein the benzotriazole compound is present in amounts of 0.05 to 0.5%. 8. A composition according to claims 1-7, wherein the benzotriazole compound is benzotriazole. 9. A composition according to claims 1-8, wherein the oxygen-releasing bleaching agent comprises in combination an inorganic perhydrate salt and a peroxyacid bleach precursor. 10. Composition according to claims 1-9, containing a heavy metal ion complexing agent in a proportion of 0.005 to 3 wt.%. 11. A composition according to claims 1-10, additionally containing a detergent component selected from a detergent builder compound and a surfactant.